Fluorinated anesthetic agents (halothane, methoxyflurane, enflurane and isoflurane) incorporation into the brain of an intact rabbit will be monitored moninvasively with 19F NMR spectroscopy. High resolution 19F spectra of the listed anesthetic agents will be obtained with a surface coil centered over the animal calvarium on a TMR spectrometer equipped with a 20-cm bore superconducting magnet. The time-course of anesthetic uptake and elimination as well as the appearance of fluorine-containing metabolites in the brain will be followed with this technique for each of the four compounds. Nature of the environments these anesthetics occupy within the brain tissue will be inferred from the observed 19F chemical shifts. The in vivo results on intact animals will be confirmed by studies of excised brain samples. After isolation, identification and structural characterization of fluorinated compounds in the excised tissues will be accomplished with NMR spectroscopy and Mass spectrometry. 19F MNR spectroscopy will allow the first direct observation of volatile anesthetic agents in a brain of a live mammal, and make possible measurement of their uptake and elimination by this organ. The results obtained from this study will be used to assess the short and long-term effects on the cellular brain function resulting from anesthesia.